I'm not sure that messing with trajectories would do anything, Terror ships are directed by the trajectories, but once it hits the city it turns into a Terror Site. In the alienDeployment: section find the STR_TERROR_MISSION entry and add "shade: 0" if you want to make all terror sites always daylight without affecting the other missions
The trick Meridian mentioned with targeting it is your best bet and also evidence of hardcoded behavior, other landings controlled by the groundTimer don't react to being targeted.
Am currently experimenting with UFO landings, will report back if I find anything else.